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Notable events involving O 23 include:

The history of HrMs O 23 as compiled on this page is extracted from O 23's patrol reports and logbooks. Corrections and details regarding information from the enemy's side (for instance the composition of convoys attacked) is kindly provided by Mr. Platon Alexiades, a naval researcher from Canada.

This page was last updated in March 2019.

10 May 1940
When Germany invaded the Netherlands HrMs O 23 and her sister ship HrMs O 24 were both still at their builders yard at Rotterdam. Both ships were not completed. O-23 had run her trials but O-24 had not, she had even never submerged.

In the early morning hours both submarines departed the builders yard for a place nearby where they were camouflaged and prepared for evacuation to the U.K. (1)

13 May 1940
Around 2100 hours HrMs O 23 (Lt.Cdr. G. Koudijs, RNN) and her sister ship HrMs O 24 (Lt.Cdr. G.B.M. van Erkel, RNN) departed the Lekhaven in Rotterdam bound for the U.K. Both submarines were were bottomed in the North Sea during daylight hours and both arrived safely at the Downs on the 15th. (1)

15 May 1940
HrMs Willem van der Zaan (Lt. Cdr. H.D. Lindner RNN), HrMs O 9 (Lt. J. Metz, RNN), HrMs O 10 (Lt. G. Quint, RNN(R)), HrMs O 23 (Lt.Cdr. G. Koudijs, RNN) and HrMs O 24 (Lt.Cdr. G.B.M. van Erkel, RNN) all departed the Downs for Porstmouth where they arrived the next day. (1)

4 Jun 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) moves from Fort Blockhouse to the Thornycroft shipyard where she will be completed. (1)

8 Jun 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was docked at the Thornycroft shipyard. (1)

25 Jun 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was undocked. (1)

5 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed the Thornycroft shipyard for Fort Blockhouse, the British submarine base at Portsmouth (HMS Dolphin). (1)

9 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departs Portsmouth for Rothesay on the Scottish West coast. She is escorted by the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN).

Off Portland they were joined by the Dutch submarines HrMs O 9 (Lt. H.A.W. Goossens, RNN) and HrMs O 10 (Lt. G. Quint, RNN(R)). (1)

11 Jul 1940
The Dutch submarines HrMs O 9 (Lt. H.A.W. Goossens, RNN), HrMs O 10 (Lt. G. Quint, RNN(R)), HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and their escort the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) arrive at Milford Haven. (1)

12 Jul 1940
The Dutch submarines HrMs O 9 (Lt. H.A.W. Goossens, RNN), HrMs O 10 (Lt. G. Quint, RNN(R)), HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and their escort the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) depart Milford Haven for Rothesay. (1)

14 Jul 1940
The Dutch submarines HrMs O 9 (Lt. H.A.W. Goossens, RNN), HrMs O 10 (Lt. G. Quint, RNN(R)), HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and their escort the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) arrive at Rothesay.

At Rothesay O 23 conducted trials and training. (1)

16 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) conducted trials and exercises in the Clyde area during which she was escorted by HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN). (1)

18 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) conducted trials and exercises in the Clyde area during which she was escorted by HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN). (1)

19 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) conducted trials and exercises in the Clyde area during which she was escorted by HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN). (1)

22 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) conducted exercises in the Clyde area with HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) and HMS Breda (Capt.(Retd.) A.E. Johnston, RN). (1)

22 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) conducted exercises in the Clyde area with HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN). Upon completion of these O 23 proceeded to Campbeltown. (1)

24 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) conducted A/S exercises off Campbeltown with HMS Tuscarora (Capt.(Retd.) E.C. Stubbs, RN). Upon completion of these exercises O 23 proceeded to Rothesay. (1)

26 Jul 1940
After a period of trials and training, HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN), departs Rothesay for Rosyth. She is escorted by the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN). (1)

27 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and her escort, the the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) arrive at Stornoway. (1)

28 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and her escort, the the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) departs Stornoway for Rosyth.

Off Scapa Flow they were joined by the British submarine HMS L 26 (Lt. P.L. Field, RN) which had just departed from there also for Rosyth. (1)

29 Jul 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN), HMS L 26 (Lt. P.L. Field, RN) and their escort, the the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) arrive at Rosyth. (1)

1 Aug 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and her escort, the the Dutch torpedo boat HrMs Z 6 (Lt.Cdr. A.C. Lunbeck, RNN) both departed Rosyth for Dundee where both ships arrive after a few hours.

At Dundee repairs were made to the diesel engines of O 23. Since leaving Portsmouth they had produced a lot of smoke. (1)

15 Aug 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel) conducted trials off Dundee. (1)

18 Aug 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Dundee for her 1st (work-up) war patrol. She was ordered to patrol in the North Sea.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

30 Aug 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) ended her 1st (work-up) war patrol at Dundee. (2)

8 Sep 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Dundee for her 2nd war patrol. She was ordered to patrol in the North Sea.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

10 Sep 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was ordered to search for the crew of a British aircraft that had crashed in the sea nearby.

The aircrew was not found and O 23 resumed her war patrol. (2)

21 Sep 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) ended her 2nd war patrol at Dundee. (2)

28 Sep 1940
Lt.Cdr. A.M. Valkenburg, RNN temporary took over command of HrMs O 23 from Lt.Cdr. G.B.M. van Erkel when he was sick. (1)

5 Oct 1940
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Dundee for her 3rd war patrol. She was ordered to patrol off the South-West coast of Norway near Bergen.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

9 Oct 1940
At 0500 hours HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) grounded at 70 feet near position 60°32'N, 04°01'E. She immediately surfaced and it was noticed that she was much nearer to the coast then thought due to the current. She dived again and remained close inshore during the day. No major damage was caused to the submarine. (2)

20 Oct 1940
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 3rd war patrol at Dundee. (2)

4 Nov 1940
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Dundee for her 4th war patrol. She was ordered to patrol off the South-West coast of Norway near Bergen.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

6 Nov 1940
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was ordered to patrol slightly further to the South. (2)

7 Nov 1940
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was ordered to patrol even further to the South off Stavanger, Norway. (2)

13 Nov 1940
Once again HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was ordered to patrol further to the South, off Obrestadt, Norway. (2)

19 Nov 1940
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 4th war patrol at Dundee. (2)

20 Nov 1940
Now off the sick list, Lt.Cdr. G.B.M. van Erkel takes up command of HrMs O 23 again. (3)

28 Nov 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Dundee for Grangemouth where she was to be docked. (3)

29 Nov 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was docked at Grangemouth. (3)

7 Dec 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was undocked. (3)

15 Dec 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was towed from Grangemouth to Rosyth for degaussing. (3)

16 Dec 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) left Rosyth for Dundee where she arrived later the same day. (3)

18 Dec 1940
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Dundee for her 5th war patrol. She was ordered to patrol off the South-West coast of Norway near Bergen.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

1 Jan 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) ended her 5th war patrol at Dundee. (2)

20 Jan 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Dundee for her 6th war patrol. She was ordered to patrol off the South-West coast of Norway to the North of Bergen.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

25 Jan 1941
At 1510 hours, near position 60°53'N, 03°47'E, a loud explosion was heard on board the submerged HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN). Three minutes later a second loud explosion was heard. It might have been that O 23 was attacked by an aircraft. Lt.Cdr. van Erkel took O 23 deep. (2)

1 Feb 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) ended her 6th war patrol at Dundee. (2)

12 Feb 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Dundee for her 7th war patrol. She was ordered to patrol off the South-West coast of Norway near Bergen.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

14 Feb 1941
Shortly after arriving in her patrol area HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) is ordered to break off her 7th war patrol and return to Dundee. She is to be sent to Gibraltar to operate from that base. (2)

17 Feb 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) ended her 7th war patrol at Dundee. (2)

23 Feb 1941
HrMs O 21 (Lt.Cdr. J.F. van Dulm, RNN) and HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) both depart from Dundee bound for Gibraltar (8th war patrol for O 23). The submarines were escorted by the British armed yacht HMS White Bear (Cdr.(Retd.) C.C. Flemming, RN). On 25 February the Free French minesweeper FFS La Moqueuse took over the escort through the Irish Sea.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

26 Feb 1941
Around 0820A/26, HrMs O 21 (Lt.Cdr. J.F. van Dulm, RNN), HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and their escort, FFS La Moqueuse, arrived at Holyhead. They departed again around 1900A/26. (4)

27 Feb 1941
Late in the afternoon, off Milford Haven, in approximate position 51°37'N, 05°28'W, HrMs O 21 (Lt.Cdr. J.F. van Dulm, RNN) and HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and their escort FFS La Moqueuse encountered the British merchant vessel Losada (6520 GRT, built 1921). As La Moqueuse was more than a mile behind both submarines the crew of the Losada thought the submarines were German U-boats and opened fire. To prevent being hit both submarines crash dived. The crew of La Moqueuse had not seen both submarines dive and was now also under the impression that a German U-boat was nearby and dropped three depth charges. O 21 was the target of the attack but sustains no damage. Both submarines surfaced shortly afterwards. (4)

28 Feb 1941
Around 0600A/28, having passed Trevose head and hour ago, FFS La Moqueuse parted company with HrMs O 21 (Lt.Cdr. J.F. van Dulm, RNN) and HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN). (4)

10 Mar 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) arrived at Gibraltar. She is escorted in by the British corvette HMS Delphinium (Cdr.(Retd.) R.L. Spalding, RN). (2)

21 Mar 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carried out A/S exercises off Gibraltar with the British destroyer HMS Forester (Lt.Cdr. E.B. Tancock, DSC and Bar, RN). (5)

24 Mar 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carries out an A/S exercise off Gibraltar with the British sloop HMS Rochester (Lt.Cdr. C.B. Allen, RN) and the British corvette HMS La Malouine (Lt.Cdr.(Retd.) R.W. Keymer, RN).

Upon completion of this exercise all three ships joined the escort of convoy HG 57 (9th war patrol for O 23).

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

25 Mar 1941

Convoy HG 57.

This convoy departed Gibraltar on 25 March 1941 and arrived in U.K. waters on 11 April 1941.

It was made up of the following merchant vessels; Aghios Spyridon (Greek, 3338 GRT, built 1905), Aldergrove (British, 1974 GRT, built 1918), Anneberg (Finnish, 2537 GRT, built 1902), Ardeola (British, 2609 GRT, built 1912), Baltallinn (British, 1303 GRT, built 1920), Baron Newlands (British, 3386 GRT, built 1928), Bollsta (Norwegian, 1832 GRT, built 1934), Caledonia (British, 1268 GRT, built 1913), Cantal (British, 3178 GRT, built 1916), Cervantes (British, 1810 GRT, built 1916), Chantilly (British, 9986 GRT, built 1923), Egyptian (British, 2868 GRT, built 1920), Empire Strait (British, 2841 GRT, built 1940), Gothland (British, 1286 GRT, built 1932), Marvia (British, 1989 GRT, built 1914), Mimosa (Greek, 3071 GRT, built 1905), Moscha D. Kydoniefs (British, 3874 GRT, built 1915), Newton Pine (British, 4212 GRT, built 1925), Octane (British (tanker) (former French), 2034 GRT, built 1939), Polo (British, 1950 GRT, built 1919), Runa (British, 1575 GRT, built 1930), Scania (Swedish, 1980 GRT, built 1901), Scottish Monarch (British, 4719 GRT, built 1938) and Trio (Swedish, 1482 GRT, built 1922).

The rescue ship Zamalek (British, 1567 GRT, built 1921).

On departure from Gibraltar the convoy was escorted by the destroyer HMS Wrestler (Lt. E.L. Jones, DSC, RN), sloop HMS Rochester (Lt.Cdr. C.B. Allen, RN), corvettes HMS La Malouine (Lt.Cdr.(Retd.) R.W. Keymer, RN), HMS Verbena (Lt.Cdr. D.A. Rayner, DSC, RNVR) and the submarine HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN).

The Aghios Spyridon returned to Gibraltar the same day the convoy had sailed.

On 27 March, HMS Wrestler was detached.

On 3 April, HrMs O 23 was detached and the light cruiser HMS Nigeria (Capt. J.G.L. Dundas, RN joined.

At 0920Z/4, HMS La Malouine was detached.

At 0845Z/5, the armed boarding vessel Hilary (Cdr. T.L. Owen, RD, RNR) joined the convoy.

At 1930Z/5, the armed boaring vessel Cavina (Cdr. C.B. Osborne, RD, RNR) joined the convoy.

On 8 April the destroyers HMS Broke (Cdr. B.G. Scurfield, RN), HMS Douglas (Cdr. W.E. Banks, DSC, RN), HMS Roxborough (Lt. V.A. Wight-Boycott, OBE, RN), HMS Salisbury (Lt.Cdr. H.M.R. Crichton, RN), corvettes HMS Abelia (T/Lt. F. Ardern, RNR), HMS Clarkia (Lt.Cdr. F.J.G. Jones, RNR) and auxiliary A/S trawlers HMS St. Elstan (T/Lt. G. Butcher, RNVR), HMS St. Kenan (T/Lt. R.R. Simpson, RNR), HMS St. Zeno (T/Lt. J.K. Craig, RNVR) and HMS Vizalma (T/Lt. M.M. Firth, RNVR).

HMS Nigeria parted company with the convoy around 1900A/9.

The convoy arrived in U.K. waters on 11 April 1941.

3 Apr 1941
At 1115 hours (GMT) HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) leaves convoy HG 57 to join convoy OG 57.

At 1300 hours smoke was sighted bearing 345° and course was set towards the convoy which was joined at 1445 hours. (2)

11 Apr 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) arrived at Gibraltar ending her 9th war patrol. (2)

23 Apr 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carried out A/S exercises off Gibraltar with two British ML's. (5)

24 Apr 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carries out an A/S exercise off Gibraltar with the British sloop HMS Wellington (Lt.Cdr. W.F.R. Segrave, RN) and the British corvette HMS Coreopsis (Lt.Cdr. A.H. Davies, RNVR).

Upon completion of this exercise all three ships joined the escort of convoy HG 60 (10th war patrol for O 23).

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

2 May 1941
At 1755 hours (GMT) HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) leaves convoy HG 60 to join convoy OG 60. (2)

3 May 1941
At 1607 hours (GMT), in position 45°25'N, 20°44'W, HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) spots convoy OG 60 that she now joined to escort it towards Gibraltar. (2)

10 May 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) arrived at Gibraltar ending her 10th war patrol. (2)

25 May 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carried out A/S exercises off Gibraltar with the British sloop HMS Scarborough (Lt. A.P. Northey, DSC, RN) and the British ASW trawler HMS Lady Hogarth (T/Lt. S.G. Barnes, RNR).

Upon completion of this exercise all three ships joined the escort of convoy HG 63 (11th war patrol for O 23).

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

1 Jun 1941
Around 2100 hours (GMT) HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) leaves convoy HG 63 and joined convoy OG 63. (2)

7 Jun 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) arrived at Gibraltar ending her 11th war patrol. (2)

12 Jun 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carried out exercises off Gibraltar with the British submarine HMS Severn (Lt.Cdr. A.N.G. Campbell, RN) and the British destroyers HMS Wrestler (Lt. E.L. Jones, DSC, RN) and HMS Vansittart (Lt.Cdr. R.L.S. Gaisford, RN)

13 Jun 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was docked in no.2 dock at Gibraltar. (5)

19 Jun 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) was undocked. (5)

25 Jun 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Gibraltar for her 12th war patrol (1st in the Mediterranean). She is to patrol in the Ligurian Sea and in the Gulf of Lyon.

While on patrol a large oil leak forced her to leave her patrol area in the Ligurian Sea and proceed towards the Spanish coast to effect repairs and to flush out the damaged tank.

For the daily and attack positions of HrMs O 23 during this patrol see the map below.

(6)

30 Jun 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN), in position 43°18'N, 10°19'E (about 20 nautical miles South of Livorno, Italy), makes a torpedo attack on a small merchant that was in ballast. Two torpedoes were fired that both missed their target. [Currently (March 2019), we have not been able to identify this target.]

Later on this day O 23 torpedoed and sank the Italian tanker Capacitas (5371 GRT, built 1920) about 7 nautical miles north-west of Cape Sant Vincent, Italy in position 43°06'N, 10°26'E.

(All times are zone -1)
0405 hours - Sighted a ship closeby. Started attack.

0409 hours - Fired two torpedoes from 2000 yards. No hits were obtained. After firing the target was seen to be a 2000 tons merchant vessel in ballast. She was not attacked again as Lt.Cdr. van Erkel would not like to disclose his presence in the hope of attacking 'bigger game'.

--------------------------------------

1100 hours - Sighted a large Southbound tanker about 6 nautical miles away, heavily laden. Started attack.

1158 hours - Fired four torpedoes from 1200 yards. Three hits were obtained and the ship capsized in a very short time. (6)

10 Jul 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) ended her 12th war patrol (1st in the Mediterranean) at Gibraltar. (6)

23 Jul 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carried out A/S exercises off Gibraltar with two British ML's. (5)

24 Jul 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carries out an A/S exercise off Gibraltar with the British destroyers HMS Vimy (Lt.Cdr. H.G.D. de Chair, RN) and HMS Vidette (Lt.Cdr. E.N. Walmsley, RN).

2 Aug 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Gibraltar for her 13th war patrol (2nd in the Mediterranean). She was to patrol in the Tyrrhenian Sea.

For the daily and attack positions of HrMs O 23 during this patrol see the map below.

(6)

16 Aug 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) attacks an Italian convoy with two torpedoes in the Tyrrhenian Sea in position 39°35'N, 13°18'E. Both torpedoes did not find a target.

(All times are zone -1)
0900 hours - Sighted two twin-engined bombers bearing 100° about 5 nautical miles away.

0913 hours - Sighted a convoy bearing 057° range 10 nautical miles. The convoy appeared to consist of at least six merchant vessels and four destroyers. Two aircraft were overhead. Started attack but could not close further then 10000 yards so a longe range shot was prepared.

1003 hours - Fired two torpedoes from a range of 5 nautical miles. The convoy showed a good close silhoutte on a course of 212° at a speed of 10 knots. Upon firing O 23 went to 130 feet. After a correct running range of about 11 minutes two explosions were heard. Immediately afterwards destroyers were heard to be approaching and a bombardment of depth charges started. About 100 were dropped. O 23 eventually went to 310 feet.

1330 hours - The intense depth charging ceased but one was still dropped about every 20 minutes until 1930 hours.

The convoy (40th Seetransport Staffel)attacked was en-route from Naples to Tripoli and was made up of the Italian merchants Maddalena Odero (5545 GRT, built 1921), Nicolo Odero (6003 GRT, built 1925), Caffaro (6476 GRT, built 1924), Marin Sanudo (5958 GRT, built 1926), Giulia (5921 GRT, built 1926) and Minatitland (7651 GRT, built 1941). They were escorted by the Italian destroyers Freccia, Euro, Dardo and the Italian torpedo boats Procione and Pegaso. (6)

21 Aug 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) ended her 13th war patrol (2nd in the Mediterranean) at Gibraltar. (6)

3 Sep 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departed Gibraltar for the U.K. where she is to refit.

For the daily positions of HrMs O 23 during this passage see the map below.

(2)

9 Sep 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) makes rendez-vouz with the British armed yacht HMS White Bear (Cdr.(Retd.) C.C. Flemming, RN) off Trevose Head. Both ships now proceeded to Holy Loch. (2)

10 Sep 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) and HMS White Bear (Cdr.(Retd.) C.C. Flemming, RN) arrive at Holy Loch. (7)

16 Sep 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) carries out torpedo trials at Loch Long with captured German torpedoes. (7)

18 Sep 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) departs Holy Loch for Dundee. She is escorted by the British armed yacht HMS Cutty Sark (Cdr.(Retd.) R.H. Mack, RN). (7)

20 Sep 1941
HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) arrived at Dundee where she is to be refitted at the Caledon Dockyard. (7)

21 Oct 1941
During her refit by the Caledon Dockyard HrMs O 23 (Lt.Cdr. G.B.M. van Erkel, RNN) is docked in the West Graving dock at Dundee. (7)

18 Dec 1941
HrMs O 23 (Lt.Cdr. K. van Dongen, RNN) was undocked. She continued her refit at Dundee by the Caledon Dockyard. (7)

30 Dec 1941
During her refit at Dundee by the Caledon Dockyard HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) is docked again. This time in the East Graving Dock. (7)

4 Jan 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) is undocked. She continued her refit at Dundee by the Caledon Dockyard. (7)

8 Feb 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted trials on the river Tay near Broughtly Ferry. (7)

11 Feb 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted trials on the river Tay near Broughtly Ferry. (7)

12 Feb 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted trials on the river Tay near Broughtly Ferry. (7)

14 Feb 1942
During 14 to 17 February HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted several trials in the Tay and Forth sanctuaries. (7)

22 Feb 1942
With her refit and initial trials completed, HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN), departs Dundee for Holy Loch for a period of training. During the passage she is escorted by the British ASW trawler HMS Quadrille (T/Lt. N.T. Chetwood, RNVR). (7)

24 Feb 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrives at Holy Loch where she begins a period of training. (7)

27 Feb 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted torpedo firing trials with captured German torpedoes off Arrochar. (7)

28 Feb 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted torpedo firing trials with captured German torpedoes off Arrochar. Upon completion of these O 23 proceeded to Holy Loch. (7)

2 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted noise trails at Loch Goil. (7)

3 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises in the Clyde area. (7)

4 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted speed trails on the measured mile in Loch Long. (7)

10 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted D/G trials off Helensburgh. (7)

11 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises in the Clyde area. (7)

12 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted attack exercises in the Clyde area. The target was HMS Adamant (Capt. R.S. Warne, RN) which was escorted by HMS Breda (Capt.(Retd.) A. E. Johnston, RN) and HMS Z 5 (T/A/Lt.Cdr. S.T. Wenlock, RNR).

Following these exercises more attack exercises were carried out during the night with HMS Z 5. (7)

13 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) returned to Holy Loch on completion of last night's exercises. (7)

16 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departs Holy Loch for the Far East. The fist leg of this passage is to Gibraltar. O 23 is escorted by the British destroyer HMS Vimy (Lt.Cdr. H.G.D. de Chair, RN) that is en-route to Portsmouth for a refit. They were also joined by the British submarine HMS Sturgeon (Lt.Cdr. M.R.G. Wingfield, RN) that was en-route to Plymouth before departing on a war patrol in the Bay of Biscay.

During the passage through the Irish Sea extreme thick fog is encountered and the ships were delayed as they had to anchor bacause of the low visibility. As O 23 loses her anchor early on the 18th all three ships made for Milford Haven where the anchor of O 23 is inspected before proceeding after a few hours.

For the daily positions of HrMs O 23 during this passage see the map below.

(7)

24 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Gibraltar. (7)

28 Mar 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Gibraltar for Alexandria. (7)

1 Apr 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) encounters a submarine South-West of Sardinia, Italy near position 38°29'N, 07°40'E. Before an attack could be started the other submarine submerged. O 23 did the same and for an hour she hunted the other submarine but no contact could be made.

According to Italian sources the other submarine was the Italian Aradam that dived immediately upon seeing another submarine as it was not certain if it was a friendly or an enemy submarine.

(All times are zone -1)
0045 hours - Near position 38°29'N, 07°40'E sighted a submarine bearing 240°. The course of the other submarine was 340°. Closed on the surface.

0052 hours - The other submarine dived.

0054 hours - O 23 also dived and obtained contact with the hydrophones but no definite bearing or range could be obtained.

0156 hours - O 23 surfaced and continued her passage towards Alexandria. (7)

3 Apr 1942
At 1800C/3, an enemy convoy made up of six merchant vessels, 2 cruisers and ten destroyers were reported in position 38°52'N, 18°50'E, steering 170° at 11 knots.

In a signal timed 2001C/3, Capt. S 1, ordered HMS Turbulent (Cdr. J.W. Linton, DSC, RN) and HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNethN) to endeavour to intercept but neither submarine had sighted the convoy by dusk the following day and continued their passage to the Adriatic and Alexandria respectively. (8)

9 Apr 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Alexandria. Passage to the Far East has to be delayed as repairs to O 23 required her to be docked. (7)

23 Apr 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was docked in the Gabari dock at Alexandria. (7)

24 Apr 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was undocked. (7)

25 Apr 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Alexandria for Port Said. (7)

26 Apr 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Port Said and entered the Suez Canal. (7)

1 May 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Aden. (7)

2 May 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Aden for Colombo. (7)

9 May 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Colombo. (7)

13 May 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for Bombay together with the Dutch submarine tender HrMs Colombia (Capt. J.L.K. Hoeke, RNN) and the Dutch submarine HrMs O 19 (Lt.Cdr. H.F. Bach Kolling, RNN(R)). They were escorted by the British destroyer HMS Scout (Lt.Cdr.(Retd.) H. Lambton, RN).

For the daily positions of HrMs O 23 during this passage see the map below.

(7)

16 May 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrives at Bombay for repairs. (7)

3 Jul 1942
With her repairs completed HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted trials off Bombay. (9)

5 Jul 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Bombay for Colombo. She makes the passage together with HrMs K XIV (Lt. J.H. Geijs, RNN). Both submarines were escorted by the Australian minesweeper HMAS Lismore (Lt.Cdr. S.H. Crawford, RANR(S)).

Because of defects HrMs K XIV returned to Bombay the next day.

For the daily positions of HrMs O 23 during this passage see the map below.

(9)

9 Jul 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) and her escort, the Australian minesweeper HMAS Lismore (Lt.Cdr. S.H. Crawford, RANR(S)), both arrive at Colombo. (9)

14 Jul 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) carries out an A/S exercises off Colombo with the British sloops HMS Falmouth (Cdr. U.H.R. James, RN) and HMS Shoreham (Cdr. E. Hewitt, RD, RNR). (9)

15 Jul 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) carries out an A/S exercises off Colombo with the British sloops HMS Falmouth (Cdr. U.H.R. James, RN) and HMS Shoreham (Cdr. E. Hewitt, RD, RNR). (9)

19 Jul 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for her 14th war patrol (1st in the Far East). She was ordered to patrol in the Malacca Staits.

For the daily and attack positions of HrMs O 23 during this patrol see the map below.

(2)

27 Jul 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) damaged the small Japanese merchant Shofuku Maru No.2 (729 GRT, built 1937) with gunfire about 10 nautical miles South-West of Penang, Malaya in position 05°07'N, 100°04'E.

(All times are zone -6)
0641 hours - Sighted a ship bearing 190°, range 5 nautical miles. The ship was steering North. Started attack. When the ship came closer it was seen to be a small coastal vessel of about 800 to 1000 tons.

0725 hours - In position 05°07'N, 100°04'E fired two torpedoes from 700 yards. One of the torpedoes was sene to run on the surface several times and to run slightly to Starboard. Both torpedoes missed.

0731 hours - Surfaced behind the target to attack it with gunfire.

0732 hours - Fired the first shot from 800 yards. The target was not armed.

0739 hours - When the 10th round was being loaded in the gun it jammed and could not be freed so gunfire had to be discontinued. By now one hit on the ships stern had been obtained.

0741 hours - Opened fire with the Oerlikon. but this too jammed after 80 rounds. Several hits had been observed. The action had now to be broken off. Withdrew to seaward. (2)

29 Jul 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) fires four torpedoes at the Japanese heavy cruisers Kumano and Suzuya escorted by the destroyers Oyashio, Hayashio and Kuroshio (all offsite links) in the Straits of Malacca about 10 nautical miles West-South-West of Pulau Perak in position 05°37'N, 98°50'E. The torpedoes missed their targets and O 23 is depth charged but manages to escape without damage.

(All times are zone -6)
0525 hours - Sighted two cruisers thought to be of the Takao-class (but later thought to be Mogami-class, and this was correct) and four destroyers bearing 185°, distance 7 nautical miles. Enemy course was 325°. Started attack altough a favourable attack position most likely could not be obtained.

After a few minutes the enemy ships had altered course towards on a zig-zag. Unfortunately this course was only steered for a very short time. Range could not be closed further then 5500 yards.

0600 hours - In position 05°37'N, 98°50'E fired four torpedoes from 5500 yards. No torpedo explosions were heard.

0612 hours - Heard two explosions thought to be depth charges. Upon returning to periscope depth one cruiser and one destroyer were seen to have altered towards. Lt.Cdr. Valkenburg quickly set up an attack with the stern torpedo tubes but before these could be fired depth control was lost and O 23 went to a greater depth. In the meantime several depth charges were dropped.

0848 hours - After having heard no HE for half an hour returned to periscope depth. One destroyer was seen bearing 310°, distance 4 nautical miles. She appeared to be searching for the attacking submarine. O 23 retired in the opposite direction.

1043 hours - Returned to periscope depth to have another look. Two destroyers and two submarine chasers were seen half a mile ahead. Lt.Cdr. Valkenburg took evasive action and went deep again.

1200 hours - Returned to periscope depth to hsve another look. Nothing in sight.

During the evening two patrolling destroyers were evaded twice. (2)

30 Jul 1942

Operation Stab.

Diversionary operation in the Bay of Bengal.

The object of this diversionary operation in which landings on the Andaman Islands simulated was to distract Japanese naval forces in conjunction with American operations in the Solomons.

To simulate landing forces three convoys were to leave India and Ceylon. These were;
' Force V ', sailing from Vizagapatam.
Tansports Blackheath (British, 4637 GRT, built 1936), Cranfield (British, 5332 GRT, built 1919) and Mahout (British, 7921 GRT, built 1925). These ships were escorted by the sloop HMIS Jumna (Cdr. J.E.N. Coope, RIN, Senior Officer) and the destroyer HMS Scout (Lt.Cdr.(Retd.) H. Lambton, RN).

' Force M ', sailing from Madras
Transports Clan McIver (British, 4606 GRT, built 1921), Custodian (British, 5881 GRT, built 1928), Hoperange (British, 5177 GRT, built 1939), Tasmania (British, 6405 GRT, built 1935) and Yuen Sang (British, 3229 GRT, built 1923). These ships were escorted by the fast minelayer HMS Manxman (Capt. R.K. Dickson, DSO, RN, Senior Officer), corvette HMS Aster (Lt. W.L. Smith, RNR) and patrol vessel HMIS Sonavati (T/A/Lt.Cdr. C.F. Smith, RINR).

' Force T ', sailing from Trincomalee
Transport (RAF Tender) Shengking (British, 2999 GRT, built 1931) and the tankers Marit Maersk (Danish, 1894 GRT, built 1938), Appleleaf (Royal Fleet Auxiliary, 5892 GRT, built 1917) and Broomdale (Royal Fleet Auxiliary, 8334 GRT, built 1937). These ships were escorted by the sloop HMIS Hindustan (A/Cdr. I.B.W Heanly, RIN, Senior Officer) and the corvette HMS Marguerite (Lt.Cdr. A.N. Blundell, RNR).

These forces were to proceed at best speed and reverse their course after dark at 1700Z/1 and return to their ports at best speed to arrive there before dusk on 2 August 1942.

' Force A ' of the Eastern Fleet was to sail from Colombo at 0400Z/31 so as to be eastward of Trincomalee by the time ' Force T ' was due to sail on the 1st August. Thereafter, ' Force A ' was to cover ' Force T ' from the eastward during the 1st and 2nd August. Subsequent movements of ' Force A ' were to depend on the situation, the force finally returning to Colombo about the 4th August.

During the night of 1/2 August, whilst forces are at sea, a wireless diversion (called Operation Spark) was to be carried out to simulate the following events.
1.) An imaginary collision was to occur in ' Force M '.
2.) One of the damaged ships was to make a plain language W/T signal reporting she had been in collision and is unable to proceed on the operation. One of the escort was to order her to keep silence and later to report to the Commander-in-Chief that ' Force M ' was unable to proceed. The Commander-in-Chief was then to postpone the operation and order all forces to return to their ports.
3.) Shore Wireless Stations were to carry out their normal W/T procedure.

Catalina Patrols were to be established well to the eastward to cover the three convoys during the short period they were at sea and ' Force A ' whilst operating in the Bay of Bengal.

At 2200F/30, the Commander-in-Chief received the following enemy report from the Dutch submarine HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNethN) which was on patrol in the Malacca Straits: ' Two cruisers of the Takao-class and four destroyers in position 05°32'N, 98°50'E. Course 340°. Speed 14 knots. Torpedoes missed. Time of Origin of the signal of HrMs O 23 was 2352Z/28.

It seemed unlikely that the enemy cruiser force, moving northwards close to the Thailand coast, was a sign of enemy reaction to the 'planted' rumours in India that seaborne forces wear being prepared to attack the Andaman Island. A more probable reason to account for this movement was a possible raid on shipping in the northern part of the Bay of Bengal or a visit to Rangoon to coincide with the establishment of the new Burmese puppet government.

HrMs O 23 was due to leave patrol in the Malacca Straits on the 31st July and return to Colombo. In view of the enemy forces reported previously by her and the forthcoming Operation Stab, she was ordered to remain on patrol until 3rd August.

Forces ' T ' and ' M ' were provided with air cover (this was not possible for ' Force V '), both by the long range reconnaissance Catalina patrols and local fighter escort, and in addition would have Force A covering them to the eastward, but ' Force V ' would be without air cover and too far away to be covered by ' Force A '. The Commander-in-Chief therefore decided to cancel the sailing of ' Force V ', but that all preparations for its departure were to continue.

In view of the enemy cruisers reported in the Malacca Straits on 29th July, The Commander-in-Chief decided to proceed with ' Force A ' from Colombo in the afternoon of 30 July. This would enable operation Stab to be carried out on the prearranged date and also admit of intercepting the Japanese force should it venture to the southern part of the Bay of Bengal.

' Force A ', comprising the battleship HMS Warspite (Capt. F.E.P. Hutton, RN, flying the flag of Vice-Admiral J.F. Somerville, KCB, KBE, DSO, RN), aircraft carriers HMS Illustrious (Capt. A.G. Talbot, DSO, RN, flying the flag of Rear-Admiral D.W. Boyd, CBE, DSC, RN), HMS Formidable (Rear-Admiral A.W.LaT. Bisset, RN), light cruisers HMS Birmingham (Capt. H.B. Crane, RN, flying the flag of Rear Admiral W.G. Tennant, CB, MVO, RN), HMS Mauritius (Capt. W.D. Stephens, RN), AA cruiser HrMs Jacob van Heemskerck (Cdr. E.J. van Holte, RNethN) and the destroyers HMAS Napier (Capt. S.H.T. Arliss, DSO, RN), HMAS Norman (Cdr. H.M. Burrell, RAN), HMAS Nizam (Lt.Cdr M.J. Clark, DSC, RAN), HrMs Van Galen (Lt.Cdr. F.T. Burghard, RNethN) and HMS Inconstant (Lt.Cdr. W.S. Clouston, RN) sailed from Colombo at 1700F/30.

Course was shaped to keep out of sight of land and to be in a position 35 miles to eastward of Trincomalee by 1000F/1.

Two air searches were sent out from ' Force A ' on 31st July. The first at 0800F to cover the section 050° to 080° ahead of the fleet to a depth of 150 miles; and the second at 1500F to search the sector 000° to 110° to a depth of 160 miles. Nothing was seen in either search.

Since no further information of the enemy cruiser force had been received, the Commander-in-Chief decided at 1100F/31 to postpone the sailing of ' Force M ' until 4 hours later and ordered a Catalina patrol to the north eastward of this force whilst at sea so as to give warning of approach of any possible enemy forces.

' Force T ' sailed from Trincomalee at the prearranged time, 0900F/1. At that time ' Force A ' was 40 miles north-east of Trincomalee, course south-west. At 1000F/1 course was altered to north-east, parallel to that of ' Force T ', and throughout the day, ' Force A ' maintained a covering position to the north-east of ' Force T '.An air reconnaissance was flown off at 0830F/1 to cover the section 340° to 000° to 130° to a depth of 150 nautical miles. This search saw nothing.

At 1040F/1, when ' Force A ' was in position 09°00'N, 21°42'E, 40 nautical miles north-east of Trincomalee, course northeast, an RDF contact was obtained on an aircraft bearing 100° range 73 miles. This was at first through to be one of the reconnaissance aircraft returning, but the absence of IFF indication being the unfortunately the rule rather than the exception. This aircraft was tracked around the fleet and passed astern at 1130F/1 on a bearing 220°, range 24 miles thence proceeded to the north-westward and finally faded on bearing 060° at 60 miles at 1215F/1. The aircraft was sighted by HMS Formidable and identified by two officers and an air lookout as a Catalina and reported as such. HMS Formidable did not send out fighters to investigate. Although the prearranged programme of the Catalina reconnaissance did not suggest one of these aircraft should be acting in this manner, the possibility was accepted in view of the lack of training of many of the newly arrived Catalina crews. Subsequent investigations and a warning of the presence of British forces broadcast from Tokyo established this was an enemy aircraft.

At noon a fighter umbrella of two Martlets was maintained by HMS Illustrious. One Martlet crashed into the barrier on deck landing. The need to economise on the fighter umbrella was governed by the necessity of conserving the Martlets. Had the aircraft referred earlier not been wrongly identified as a Catalina, The Commander-in-Chief was convinced that it could have been intercepted by Martlets that were ranged at readiness in both aircraft carriers.

A further air search was sent out at 1500F/1 to cover the sector from 000° to 110° to a depth of 150 miles but nothing was seen.

At 1800F/1, one of the Fulmar search aircraft made an emergency landing on HMS Illustrious, but crashed on desk due to a fractured oil pipe spraying the pilot’s windscreen, and was badly damaged.

At 1830F/1, all the search aircraft except two Fulmars had returned to their carriers. The two missing aircraft reported to HMS Formidable by wireless that they were lost and requested D/F bearings. The Commander-in-Chief at once ordered wireless silence to be broken to home these aircraft. The fleet was turned at 1840F/1 to close one of the aircraft when bearing had been definitely established by D/F and RDF. Searchlights were burned at dusk to assist returning aircraft and at 1920F/1 Very’s lights were sighted to the south-west. A few minutes later one of the aircraft was sighted and closed the carriers. Unfortunately, the aircraft by this time so short of petrol that it had to force land in the sea. The crew were picked up by HMAS Norman.

By 2000F/1. ' Force A ', which had become somewhat dispersed during reversal of course and whilst locating the crew of the aircraft, was reformed and course altered to the north west. Unfortunately nothing further was heard or seen of the other missing Fulmar with the exception of one report that a light had been seen to the eastward. A night search for the survivors of this aircraft was considered, but as they would have left the convoy uncovered to the northeast, The Commander-in-Chief decided it was preferable to return to this area at dawn and carry out a daytime air search. The Commander-in-Chief therefore continued to the north-west and at 0100F/2 in position 11°30'N, 82°15'E, course was reversed to the south-east and at daylight course was altered to south.

The wireless diversion (Operation Spark) was carried out as previously arranged during the night at 2300F/1 and appears to have been fully effective.

At 0630F/2, a thorough air search was sent out to look for survivors of the Fulmar which had been lost the previous evening. Whilst this attack was continuing, ' Force A ' was manoeuvred in the area in which it was estimated that the survivors might have landed. No survivors were located and it must be presumed with regret that the crew of two was lost. Catalinas which would be operating through this area were requested to keep a good lookout for survivors.

At 1030F/2, despatches were transferred by HMAS Norman from HMS Warspite to HMS Illustrious and thence sent by aircraft to Trincomalee for onward transmission. At 1100F/2, HMS Formidable flew off two Martlets as fighter umbrella. At 1112F/2, both carriers reported RDF contact on an aircraft bearing 055°, range 55 miles. HMS Formidable directed two Martlets onto this aircraft. When the fighters sighted the enemy flying boat at 10000 feet they first thought it was a Catalina, but on approaching closely identified it as a Japanese flying boat Navy Type 97, and promptly shot it down in approximate position 09°26'N, 83°16'E. The flying boat, which appeared to be taken completely by surprise, gave no return fire and after the second burst of fire from the Martlets, caught fire, disintegrated and fell in flames. No survivors were seen.

In the meantime at 111F/2 a further two Martlets each were flown off by the carriers. One of these Martlets from HMS Formidable crashed into the sea on taking off. The pilot was rescued by HrMs Jacob van Heemskerck.

A fighter umbrella of two Martlets was maintained for the rest of the day by HMS Illustrious. At 1530F/2 one of these Martlets appeared to have an engine failure and crashed into the sea whilst approaching to land on. The pilot was lost.

At about 1100F/2, the Commander-in-Chief had received information from the Flag Officer, Ceylon that Air Headquarters Bengal considered there were indications of naval activity south of the Andamans at 2300Z/31, that pointed to the possibility of an attack on Madras at dawn on the 3rd August and that the information on which this was based was from a most secret source. Flag Officer, Ceylon, had also informed Admiralty and the Deputy Commander in Chief, Eastern Fleet.

There was nothing in Air Headquarters Bengal signal to indicate what was the nature of the naval activity which had been reported nor the reliability of the source. The Commander-in-Chief immediately requested Flag Officer, Ceylon to obtain amplification of this report.

Although a dawn attack by this Japanese naval force on Madras on 3rd August was possible, The Commander-in-Chief considered the following factors would make it very improbable.
1.) ' Force A ', probably having been sighted by the Japanese flying boat A.M. 1st August.
2.) ' Force A ', breaking wireless silence to endeavour to recover aircraft on the evening of 1st August. 3.) The wireless diversion (Operation Spark), carried out on the night of 1st/2nd August.

Nevertheless the Commander-in-Chief felt that he could not disregard Air Headquarters Bengal report and he therefore decided to proceed at once to Trincomalee and refuel destroyers in preparation for an extension of the present operation. he informed Their Lordships of his intentions in his signal 1215Z/2. Course was altered at 1215F/2 to the westward and speed increased to reach Trincomalee before dark.

' Force A ' entered Trincomalee at 1915F/2 and refuelling of destroyers commenced at once and as completed at 2200F/2 when it had been intended that ' Force A ' should sail again.

Additional Catalina patrols had been arranged to cover the approaches to Madras from the east and south-east, from p.m. 2nd August until daylight 3rd August.

It was not until ' Force A ' arrived at Trincomalee at 1900F/2 that the Commander-in-Chief received a message from Air Headquarters India (Flag Officer Ceylon’s 0744/2) stated that they did not agree with the deductions nor authorize the message from Air Headquarters Bengal. After discussion with Rear Admiral Commanding, Aircraft Carriers and Rear Admiral Commanding Fourth Cruiser Squadron, the Commander-in-Chief decided that there was no real basis for this report and in view of HMS Formidable and HMS Birmingham being required at an early date to return to Kilindini for Operation Streamline Jane, the Commander-in-Chief decided the ' Force A ' should return to Colombo.

The Commander-in-Chief informed Their Lordships of his revised intentions in his message 1649Z/2.

' Force A ' sailed accordingly from Trincomalee at 0600F/3 and shaped course for Colombo keeping out of sight of land. During the day a safety patrol of one aircraft was maintained 30 miles ahead of the Fleet. This patrol was carried out by Walrus aircraft from cruisers during the afternoon but had to be cancelled owing to rising wind and sea. A fighter umbrella of two Martlets was maintained throughout the day.

At 1030F/3, HMS Manxman, who was returning from Madras to Colombo, as about 30 miles south-west of ' Force A '. An aircraft was sent to order her to join ' Force A ', which she did at 1300F/3.

At 1430F/3, HMS Illustrious obtained an RDF contact on an aircraft bearing 60° and at 1440F/3, HMS Warspite obtained a doubtful contact on the same bearing at a range of 50 miles. Both contacts faded ten minutes later. At that time ' Force A ' was in position approximately 06°40'N, 82°10'E. The RDF contact may have been a Japanese flying boat, but more probably an aircraft operating from China Bay as no Catalina were know to be in that area. The uncertainty and short duration of the contacts rendered fighter interception impracticable.

Before leaving Trincomalee the Commander-in-Chief had proposed to Air Officer Commanding, Ceylon that opportunity should be taken to exercise that Fighter Direction of shore based fighters from HM ships and any other air exercises he might wish to carry out.

From 1645F/3 to 1800F/3, successful fighter direction exercise was carried out using two Fulmars from HMS Illustrious as the enemy. R/T communication was obtained quickly and no difficulty experienced in directing the Hurricanes on to their target. From 1800F/3 till dusk these two Fulmars took over the duties of fighter umbrella.

The next air exercise was a night shadowing exercise and a night torpedo and bombing attack on the fleet.

At 1850F/3, HMS Illustrious reported an aircraft in sight bearing 190° and directed the fighter umbrella of two Fulmars to investigate. This aircraft which was clearly in sight from HMS Warspite was a flying boat just visible above the horizon and though it presented characteristics of a Catalina, it could not definitely be identified as such. HMS Illustrious directed the Fulmars on to the target, a warning being given by R/T that the aircraft was possibly friendly. Unfortunately the designation 'Bandit' i.e. enemy aircraft, as opposed to 'Bogey' i.e. unidentified aircraft, was employed by the Fighter Directing Officer. For this and other reasons which are being investigated by a Board of Enquiry one of the Fulmars opened fire on this flying boat, which proved to be a Catalina. Fire was ceased directly the pilot realized his mistake but the Commander-in-Chief regret to report that one airman was killed and two injured and the Catalina’s rudder damaged. The Fulmars returned to HMS Illustrious and from subsequent signals it appeared that the Catalina was still airborne and returning to her base. As a safety measure HMS Mauritius and HMS Manxman were detached to search the area in case the Catalina was forced to land, but were recalled when it was clear from RDF bearings that the Catalina was proceeding to Koggala.

During the night of 3rd/4th August the shore based reconnaissance aircraft were unable to locate ' Force A ' and in consequence no attacks were delivered. From 0530F/4 to 0645F/4 another fighter direction exercise with shore based aircraft was successfully carried out.

' Force A ' arrived at Colombo at 0900F/4. (10)

2 Aug 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) attacked a Japanese convoy and torpedoed and heavily damaged the Japanese army cargo ship Zenyo Maru (6440 GRT, built 1937, offsite link) about 30 nautical miles North-West of Penang, Malaya in position 05°36'N, 99°48'E. The Japanese ship burns out and was later towed to Singapore. She was declared a total loss.

(All times are zone -6)
0840 hours - Sighted a convoy made up of one armed merchant with guns forward and aft that was acting as escort. This ship was followed by four merchant vessels. Started attack.

0926 hours - In position 05°33'N, 99°48'E fired one torpedo on the first merchant ship behind the escort from 800 yards. Unfortunately the torpedo ran straight to the bottom and detonated 7 seconds after firing. No damage was caused to O 23. After this explosion the escort immediately turned away followed by the first merchant ship.

0930 hours - The second merchant ship however waited several minutes so this was fired upon with two torpedoes from the training torpedo tubes. Range was 900 yards. Two faint explosions were heard 50 and 60 seconds after firing which was the correct running range.

0935 hours - Two stern torpedoes were fired on the last ship from 1000 yards. A huge explosion occured amidships on thuis ship 60 seconds after firing. This ship was at once full ablaze. The other ships were now seen to have turned to the North. Depth charges were dropped at irregular intervals most likely by the escort.

As the ship that was hit did not appeared to be sinking it was decided to finish it off with the deck gun. However the escort turned back and dropped depth charges, some of which were quite close. The gun attack was abandoned and O 23 went deep and cleared the area. (2)

10 Aug 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 14th war patrol (1st in the Far East) at Colombo. (2)

24 Aug 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was docked in the inner graving dock at Colombo. (11)

29 Aug 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was undocked. (11)

1 Sep 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for her 15th war patrol (2nd in the Far East). She was ordered to patrol in the Andaman Sea, Malacca Staits and North-West coast of Sumatra.

For the daily and attack positions of HrMs O 23 during this patrol see the map below.

(2)

9 Sep 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) made a torpedo attack on a Japanese merchant vessel about 40 nautical miles South-West of Phuket in position 07°30'N, 98°03'E. Two torpedoes were fired but both missed their target.

(All times are zone -6.5)
0900 hours - Heard HE bearing 300° but nothing could be seen in that direction due to heavy rain squalls.

0910 hours - Sighted, for a very short moment, a merchant ship bearing 292°, distance 4 nautical miles. Started attack. The ship was later seen to be of about 3000 to 4000 tons and was armed with a gun forward and aft. Decided to attack dispite a minumum chance of succes owning to the possible bad depth keeping of the torpedoes in the bad weather.

0945 hours - In position 07°30'N, 98°03'E fired two torpedoes from 1700 yards. Two detonations were heard 6 and 7.5 minutes after firing the first torpedo. These were end of run detonations. After the first explosion the target made off to the South in a direction of 150° and started zig-zagging. (2)

19 Sep 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 15th war patrol (2nd in the Far East) at Colombo. (2)

17 Oct 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for her 16th war patrol (3rd in the Far East). She was ordered to patrol in the Malacca Staits.

For the daily and attack positions of HrMs O 23 during this patrol see the map below.

(2)

25 Oct 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) torpedoed and damaged the Japanese merchant Shinyu Maru (4622 GRT, built 1919) off Penang, Malaya in position 05°28'N, 99°56'E.

(All times are zone -6.5)
0840 hours - Sighted smoke bearing 158°.

0850 hours - Sighted a ship bearing 163°, distance about 15 nautical miles. The ships course appeared to be South-West.

0905 hours - Sighted smoke bearing 170°. This smoke appeared to be from four ships, distance about 15 nautical miles, they were also on a South-Westerly course. These ships were all merchant vessels of about 5000 tons. It was later seen that an A/S trawler was also in the area.

1118 hours - Initially thought they were heading toward Rangoon but at a signal from the trawler all ships set course for the Northern entance of Penang. Started attack.

1145 hours - In position 05°34'N, 99°54'E fired two bow torpedoes at the first ship of the convoy behind the A/S trawler. Range was 1300 yards. One hit was observed just before the bridge. The ship was seen to list to Port and also to turn round to Port. Immediately after firing the second torpedo Lt.Cdr. Valkenburg turned O 23 to attack the second ship line with the two remaining bow torpedoes. It was his intention to attack the third ship with the two torpedoes in the training (deck) torpedo tubes and the fourth ship with the two torpedoes in the stern torpedo tubes.

1147 hours - Fired two bow torpedoes at the second ship in line. Range was also 1300 yards. Immediately after firing the first torpedo the first ship in line was hit by the first salvo. This resulted in the second ship altering course and increasing speed so both torpedoes missed. As the third and fourth ship also altered course the attack on them was abandoned. The convoy now fled to seaward and was later seen to make a detour to the North before entering Penang.

1151 hours - Fired one torpedo from the training tubes at the damaged merchant ship. Range on firing was 1100 yards. The torpedo was not seen to run and did not explode.

1159 hours - Fired one torpedo from the stern tubes at the damaged merchant ship from 1100 yards. One minute after firing an explosion occured about 20 yards before the stem of the ship.

1201 hours - Fired the second and last torpedo from the stern torpedo tubes at the damaged merchant ship from 1100 yards. This one exploded about 20 yards abaft the stem of the ship 68 seconds after firing. Both these last torpedoes exploded very near to the target and possibly hit the bottom.

1204 hours - The ship was seen to steam slowly away towards Penang escorted by the A/S trawler. O 23 meanwhile cleared the area

Depth charges now exploded between 1200 and 1223 hours but none did any damage. Through none were seen it was thought that aircraft were now hunting O 23. (2)

7 Nov 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 16th war patrol (3rd in the Far East) at Colombo. (2)

28 Nov 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for her 17th war patrol (4th in the Far East). She was ordered to patrol in the Malacca Staits.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

20 Dec 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 17th war patrol (4th in the Far East) at Colombo. O 23 suffers from many defects and will be refitted at Colombo before she is able to go on patrol again. (2)

22 Dec 1942
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was docked in the inner graving dock at Colombo. (12)

2 Jan 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was undocked. (13)

14 Feb 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was again docked in the inner graving dock at Colombo. (13)

18 Feb 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was undocked. (13)

4 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted engine trials off Colombo. (13)

8 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo. (13)

9 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Devonshire (Capt. D. Young-Jamieson, RN) which had just left the dry dock.

On completion of the exercises HMS Devonshire set course to proceed to the Seychelles. (14)

10 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Overdale Wyke, HMS Hoxa (T/Lt. H.P Davies, RNR), HMS Okapi and HMIS Rajputana (Lt W.G. Coltham, RIN). (13)

11 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMAS Gawler (Lt.Cdr.(Emgy.) W.J. Seymour, RAN). (13)

13 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Scout (Lt. R.G. Woodward, RN). (13)

15 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Overdale Wyke and HMS Verbena (Lt. J.R. Freeman, RNR). (13)

16 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo. Practice attacks were made on the Dutch accomodation / depot ship Plancius by all the officers of O 23. (13)

20 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Tulip (Lt. C.W. Leadbetter, RNR), HMS Hoxa (T/Lt. H.P Davies, RNR) and HMS Okapi. (13)

22 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Overdale Wyke, HMS Okapi and HMAS Tamworth (T/Lt. W.H. Deans, RANR(S)). (13)

24 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Tulip (Lt. C.W. Leadbetter, RNR). (13)

25 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo. Practice attacks were made on the Dutch stores ship HrMs Zuiderkruis by all the officers of O 23. (13)

26 Mar 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Hoxa (T/Lt. H.P Davies, RNR) and HMAS Tamworth (T/Lt. W.H. Deans, RANR(S)). (13)

30 Mar 1943
During the night of 30-31 March 1943 HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted night exercises off Colombo. (13)

1 Apr 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Tulip (Lt. C.W. Leadbetter, RNR) and HMS Overdale Wyke. (13)

3 Apr 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Scout (Lt. R.G. Woodward, RN) and HMAS Lismore (T/Lt. L.C.G. Lever, RANR(S)). (13)

7 Apr 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Hoxa (T/Lt. H.P Davies, RNR) and HMS HDML 1082 (T/Lt. G.G. MacPherson, RNVR).

During the night of 7 to 8 April 1943 HrMs O 23 conducted night exercises off Colombo. (13)

9 Apr 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo. (13)

12 Apr 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMS Verbena (Lt. J.R. Freeman, RNR). (13)

23 Apr 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted exercises off Colombo with HMAS Maryborough (A/Cdr. G.L. Cant, RAN) and HMAS Lismore (T/Lt. L.C.G. Lever, RANR(S)). (13)

27 Apr 1943
During the night of 27-28 April 1943 HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) conducted night exercises off Colombo. (13)

7 May 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was docked in the outer graving dock at Colombo. (13)

10 May 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was undocked. (13)

14 May 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) is slightly damaged when the Dutch accomodation / depot ship Plancius slips here moorings during strong winds. O 23 was moored alongside and was damaged by a buoy. A diver found some damage to the sumarine which required her to dock again for repairs. (13)

16 May 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was docked at Colombo. (13)

18 May 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was undocked.

During the night of 18-19 May 1943 O 23 conducted night exercises off Colombo.

After 5 months of waiting for spare parts to arrive and repairs O 23 is fit for operational patrols again. (13)

22 May 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for her 18th war patrol (5th in the Far East). She was to patrol in the Northern entrance to the Malacca Straits.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

6 Jun 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 18th war patrol (5th in the Far East) at Colombo. (2)

15 Jun 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for her 19th war patrol (6th in the Far East). She was to patrol in the Malacca Straits and to carry out a special operation.

For the daily and attack positions of HrMs O 23 during this patrol see the map below.

(2)

17 Jun 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) makes a short call at Trincomalee to take on board material and 2 British army officers and 3 Chinese for the special operation. (2)

25 Jun 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) carries out Special Operation GUSTAVUS II. A rendez-vouz, South of the Sembilan Islands, was made with a junk to transfer some of the persons taken on board in Trincomalee. Some of the crew of the junk were taken on board O 23 for return passage to Colombo. No stores were needed so these were not transferred. (2)

26 Jun 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) makes a torpedo attack on a small empty Japanese tanker near the One Fathom Bank in the Malacca Staits in position 03°02'N, 100°40'E

(All times are zone -6.5)
1517 hours - Surfaced for a surface patrol in the area. Immediately sighted a ship through the periscope. It was not seen from the bridge. The ship was in bearing 118°, distance was about 8 nautical miles, enemy course was about 300°.

1520 hours - Dived and commenced an attack as soon as the ship became visible through the periscope. It was first thought to be very large but when it came closer it was seen to be a small empty tanker of about 1000 tons or possibly even less.

1614 hours - In position 03°02'N, 100°40'E fired two torpedoes from 700 yards. No hits were obtained and it is quite likely the torpedoes ran under. The target made a sharp alteration towards and fearing a counter attack with depth charges O 23 had to take evasive action. After a few minutes the target altered course and zig-zagged away. It was decided not to surface for gun action as the tanker was armed and the element of surprise was now gone. (2)

6 Jul 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 19th war patrol (6th in the Far East) at Colombo. (2)

24 Jul 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for her 20th war patrol (7th in the Far East). She was to patrol off Port Blair and in the Malacca Straits. She was also ordered to carry out a special operation.

For the daily positions of HrMs O 23 during this patrol see the map below.

(2)

28 Jul 1943
At 0426 hours (zone -6.5) HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) encounters the Japanese light cruiser Kashii (offsite link) about 30 nautical miles West off Little Andaman Island in position 10°50'N, 93°02'E. O 23 was unable to attack as she was most likely spotted and the Japanese took evasive action. (2)

4 Aug 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) carries out Special Operation GUSTAVUS III. A rendez-vouz, South of the Sembilan Islands, was made with the same junk as on 25 June 1943 to transfer some of the persons taken on board in Colombo. Also stores were transferred to the junk. (2)

5 Aug 1943
At 1920 hours (zone -6.5) HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) sights a ship very nearby about 30 nautical miles South-South-West of Penang near position 04°55'N, 100°05'E. The torpedo tubes could not be brought to the ready quickly enough for an attack. O 23 surfaced and gave chase but she was spotted by the enemy and attacked with gunfire. O 23 had to submerge and was depth charged by an escort vessel but she suffered no damage and was able to slip away. (2)

16 Aug 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) ended her 20th war patrol (7th in the Far East) at Colombo. (2)

24 Aug 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was docked in the inner graving dock at Colombo. (13)

31 Aug 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) was undocked. (13)

8 Sep 1943
As some repairs were made to the pressure hull of HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN), she made a deep dive off Colombo today. No problems were found. (13)

11 Sep 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Colombo for Aden. This is the first leg of the trip to the U.K. where she was to refit.

For the daily positions of HrMs O 23 during this passage see the map below.

(2)

21 Sep 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Aden. (2)

22 Sep 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Aden for Port Said. (2)

27 Sep 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Port Said. (2)

3 Oct 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Port Said for Malta. (2)

7 Oct 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Malta. (2)

8 Oct 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Malta for Gibraltar. She makes the passage in convoy MKS-27. (2)

14 Oct 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Gibraltar. (2)

20 Oct 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Gibraltar for Holy Loch. (2)

29 Oct 1943
Early in the morning, HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN), makes rendez-vouz off Bishops Rock with her escort, the British minesweeper HMS La Capricieuse (Lt.Cdr.(Retd.) C.M. Norman, RN). (2)

30 Oct 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Holy Loch. (2)

1 Nov 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) departed Holy Loch for Dundee. She makes the passage together with the British submarine HMS Spiteful (Lt.Cdr. F.H. Sherwood, DSC, RCNVR). The submarines are escorted by the British minesweeper HMS La Capricieuse (Lt.Cdr.(Retd.) C.M. Norman, RN).

Early on the 3rd, off Scapa Flow, the other two ships left O-23 and the British ASW trawler HMS Thornwick Bay (A/Skr.Lt. J. Windram, RNR) took over the escort. (2)

4 Nov 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) arrived at Dundee. (2)

16 Nov 1943
HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) shifted from Dundee to Grangemouth where she was to refit. (15)

27 Jan 1944
During her refit by the Grangemouth Dockyard HrMs O 23 (Lt.Cdr. A.M. Valkenburg, RNN) is docked. (15)

2 May 1944
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) is undocked. She continued her refit at Grangemouth by the Grangemouth Dockyard. (15)

19 Nov 1944
During her refit by the Grangemouth Dockyard HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) is docked. (15)

15 Dec 1944
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) is undocked. She continued her refit at Grangemouth by the Grangemouth Dockyard. (15)

23 Dec 1944
HrMs Dolfijn (Lt.Cdr. J.B.M.J. Maas, RNN) and HrMs O 24 (Lt.Cdr. P.J.S. de Jong, RNN) conducted exercises off Dundee. (16)

12 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) ended her refit at the Grangemouth Dockyard. (15)

13 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) shifts from Grangemouth to Rosyth. (15)

14 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) shifts from Rosyth to Dundee. (15)

20 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) and HrMs O 15 (Lt. R.W. van Lynden, RNN) both conducted exercises of Dundee. They made pratice attacks on each other. (17)

22 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Dundee for Loch Alsh. She was escorted by HMS Loch Monteith (T/Lt. W.E. Turner, RNVR). (15)

23 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Loch Alsh. (15)

26 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Loch Alsh for Holy Loch where she will undergo a period of training.

She makes the passage together with HMS Tactician (Lt.Cdr. L.N.A. Jewell, DSC, MBE, RN) and HMS Spearhead (T/A/Lt.Cdr. R.E. Youngman, RNR). The three submarines were escorted by HMS Shikari (Lt. E.H.U. Cautley, RNVR). (15)

27 Feb 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Holy Loch. (15)

2 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted exercises in the Clyde area. (15)

3 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted exercises in the Clyde area. (15)

4 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted exercises in the Clyde area. (15)

6 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted speed trials on the measured mile in Loch Long. (15)

7 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted speed trials on the measured mile in Loch Long. (15)

8 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Sardonyx (Lt.Cdr. L.F.L. Hill, RNR) and HMS Inman (T/A/Lt.Cdr. H.E. Petre, RNR) served as targets. (15)

9 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Sardonyx (Lt.Cdr. L.F.L. Hill, RNR) and HMS Bridgewater (Cdr.(Retd.) R.H. Mack, RN) served as targets. (15)

10 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted radar and attack exercises in the Clyde area during which HMS Sardonyx (Lt.Cdr. L.F.L. Hill, RNR) and HMS Bridgewater (Cdr.(Retd.) R.H. Mack, RN) served as targets. (15)

12 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Sardonyx (Lt.Cdr. L.F.L. Hill, RNR) and HMS Bridgewater (Cdr.(Retd.) R.H. Mack, RN) served as targets. (15)

13 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted exercises in the Clyde area. (15)

15 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted exercises in the Clyde area. (15)

16 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Sardonyx (Lt.Cdr. L.F.L. Hill, RNR) and HMS Bridgewater (Cdr.(Retd.) R.H. Mack, RN) served as targets. (15)

17 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Shikari (Lt. E.A. Tyrer, DSC, RN) and HMS Bridgewater (Cdr.(Retd.) R.H. Mack, RN) served as targets. (15)

18 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted noise trials at Loch Goil. Upon completion of these O 23 returned to Holy Loch from where she departed for Tobermory later this day. (15)

19 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Tobermory. (15)

21 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted A/S exercises off Tobermory with HMS Mounsey, HMS Loch Glendhu (Lt.Cdr. E.G.P.B. Knapton, RN), HMS Welcome (T/A/Lt.Cdr. W. Downing, RNVR) and HMS Felicity (T/A/Lt.Cdr. S.F. Harmer-Elliot, RNVR). (15)

22 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted A/S exercises off Tobermory with HMS Mounsey and HMS Loch Glendhu (Lt.Cdr. E.G.P.B. Knapton, RN). Also a practice attack was carried out during which HMS Loch Achray (T/A/Lt.Cdr. L.H. Stammers, RNVR) served as the target. (15)

23 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted A/S exercises off Tobermory with HMS Liberty (T/Cdr. J.S. Roe, DSC, RNVR) and HMS Loch Achray (T/A/Lt.Cdr. L.H. Stammers, RNVR). (15)

25 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted gunnery exercises off Tobermory. These were followed by A/S exercises with HMS Welcome (T/A/Lt.Cdr. W. Downing, RNVR) and HMS Felicity (T/A/Lt.Cdr. S.F. Harmer-Elliot, RNVR). (15)

26 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted A/S exercises off Tobermory with HMS Welcome (T/A/Lt.Cdr. W. Downing, RNVR), HMS Felicity (T/A/Lt.Cdr. S.F. Harmer-Elliot, RNVR), HMSAS Natal (T/Lt.Cdr. D.A. Hall, DSC, SANF(V)) and HMS Trondra (T/Lt. W.R. Russell, RNVR).

Upon completion of these exercises O 23 proceeded to Loch Alsh. (15)

27 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Loch Alsh. (15)

28 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted A/S exercises off Loch Alsh with HMS Philante (Cdr. M.J. Evans, OBE, RN), HMS Pevensey Castle (Cdr. E. Hewitt, RD, RNR), HMS Kenilworth Castle (A/Lt.Cdr. J.O. Williams, RNR), HMS Launceston Castle (Lt. R.M. Roberts, RNR) and HMS Caistor Castle (A/Lt.Cdr. B.J. Bowick, RNVR). These included night exercises. (15)

30 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises off Loch Alsh during which HMS Uproar (Lt. J.N. Devlin, DSC, RN) served as the target.

These attack exercises were followed by A/S exercises off Loch Alsh with HMCS Charlottetown (T/Lt.Cdr. J. Harding, RCNR), HMCS Antigonish (T/Lt.Cdr. R.D. Barrett, RCNR) and HMCS Kirkland Lake (Lt.Cdr. N.V. Clark, OBE, RCNR). (15)

31 Mar 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted indepent exercises off Loch Alsh. (15)

1 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises off Loch Alsh during which HMS Philante (Cdr. M.J. Evans, OBE, RN) served as the target. During these exercises HMS Philante was escorted by HMCS Charlottetown (T/Lt.Cdr. J. Harding, RCNR), HMCS Antigonish (T/Lt.Cdr. R.D. Barrett, RCNR) and HMCS Kirkland Lake (Lt.Cdr. N.V. Clark, OBE, RCNR). (15)

3 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises off Loch Alsh during which HMS Vitality (Lt. W.T.J. Fox, RN) served as the target. (15)

5 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN), HMS Vitality (Lt. W.T.J. Fox, RN) and HMS Scotsman (Lt. A.H.B. Anderson, DSC, RNR) conducted A/S exercises off Loch Alsh with HMS Philante (Cdr. M.J. Evans, OBE, RN) and ships from the 2nd Escort Group. Also practice attacks were made on HMS Philante. (15)

6 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted indepentent exercises off Loch Alsh followed by A/S exercises off Loch Alsh with HMS Loch Fada (Cdr. B.A. Rogers, RD, RNR) and HMS Wild Goose (Cdr. D.E.G. Wemyss, DSO, DSC and Bar, RN). (15)

7 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted A/S exercises off Loch Alsh with HMS Loch Achray (T/A/Lt.Cdr. L.H. Stammers, RNVR) and HMS Loch More (Lt.Cdr. R.A.D. Cambridge, DSC, RD, RNR). (15)

8 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Loch Alsh for Holy Loch. (15)

9 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Holy Loch. (18)

11 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted gunnery exercises in the Clyde area. (18)

14 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Hastings (A/Cdr. E.A. Stocker, DSC, RN) served as the target. (18)

15 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted gunnery exercises followed by attack exercises in the Clyde area during which HMS Hastings (A/Cdr. E.A. Stocker, DSC, RN) served as the target. (18)

16 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted night radar exercises followed by attack exercises in the Clyde area during which HMS Hastings (A/Cdr. E.A. Stocker, DSC, RN) served as the target. (18)

17 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Hastings (A/Cdr. E.A. Stocker, DSC, RN) served as the target. These were followed by gunnery exercises. (18)

18 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Hastings (A/Cdr. E.A. Stocker, DSC, RN) served as the target. Following these exercises O 23 proceeded to Loch Goil for sound trials. Upon completion of these sound trials O 23 proceeded to Holy Loch. (18)

26 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) was docked in AFD 7 at Holy Loch. (18)

28 Apr 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) was undocked. (18)

14 May 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted noise trials at Loch Goil. (18)

19 May 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Holy Loch for Dundee.

Passage towards Scapa Flow was made together with HMS Vagabond (Lt. I.M. Stoop, DSC, RN ) with escort provided by HMS Bridgewater (Cdr.(Retd.) R.H. Mack, RN).

Off Scapa Flow O 23 is joined by HrMs Tijgerhaai (Lt.Cdr. A. van Altena, RNN) escorted by HMS Bute (T/S.Lt. G.F. Kettle, RNVR) for onward passage to Dundee while the other ships proceeded towards Scapa Flow. (18)

22 May 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Dundee. (18)

24 May 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Dundee for Rotterdam. She makes the passage together with HrMs Tijgerhaai (Lt.Cdr. A. van Altena, RNN). They are escorted by the British Auxiliary patrol trawler HMS Fort Rose (A/Ch.Skr. W.J. Barlow, RNR). (18)

26 May 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Rotterdam. (18)

28 Jun 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Rotterdam for Dundee. She makes the passage together with HrMs Tijgerhaai (Lt.Cdr. A. van Altena, RNN). They are escorted by the British escort destroyer HMS Fernie (Lt. J.A. Tricker, RN). (18)

30 Jun 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Dundee. (18)

1 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Dundee for Holy Loch. (18)

3 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Holy Loch to resume her training period cut short last May when she was sent to Rotterdam when the Netherlands were liberated. (18)

5 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted exercises in the Clyde area. These included night exercises. (18)

6 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted A/S exercises off Campbeltown with HMS La Cordeliere (T/Lt. F.A. Haworth, RNVR) and HMS Clover (Lt. R.P. Booth, RNVR). O 23 proceeded to Holy Loch on completion of these exercises. (18)

7 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Hastings (A/Cdr. E.A. Stocker, DSC, RN) served as the target. These included night exercises. (18)

8 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) proceeded to Holy Loch on completion of last night's exercises. (18)

9 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area during which HMS Kihna (Cdr.(Retd.) T.J.T.C. Jenks, RN) served as the target. (18)

11 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) conducted attack exercises in the Clyde area. The target was HMS Icarus (Cdr.(Retd.) M.W. Ewart-Wentworth, RN) that was escorted by HMS Brilliant (A/Cdr.(Retd.) A.R.W. Sayle, RD, RNR). These attack exercises were followed by gunnery exercises on a target that was being towed by HMS Kihna (Cdr.(Retd.) T.J.T.C. Jenks, RN). (18)

12 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) was docked in AFD 7 at Holy Loch. (18)

13 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) was undocked. (18)

17 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Holy Loch for Gibraltar. This was the first leg of the trip to Australia for another deployment in the Far East.

For the daily positions of HrMs O 23 during this passage see the map below.

(18)

22 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Gibraltar. (18)

23 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Gibraltar for Malta. (18)

27 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Malta. (18)

30 Jul 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Malta for Port Said. (18)

2 Aug 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Port Said. (19)

6 Aug 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Port Said for Aden. (19)

10 Aug 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Aden. (19)

12 Aug 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Aden for Colombo. (19)

20 Aug 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Colombo. (19)

21 Aug 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Colombo for Fremantle. (19)

3 Sep 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Fremantle. As the war with Japan was now over she prepared to return to the Dutch East Indies. (19)

21 Sep 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) departed Fremantle for Batavia in the Dutch East Indies.

For the daily positions of HrMs O 23 during this passage see the map below.

(19)

29 Sep 1945
HrMs O 23 (Lt.Cdr. A.J. Schouwenaar, RNN) arrived at Batavia. (19)